1# dup.m4 serial 7
2dnl Copyright (C) 2011-2021 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_FUNC_DUP],
8[
9  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
11  m4_ifdef([gl_MSVC_INVAL], [
12    AC_REQUIRE([gl_MSVC_INVAL])
13    if test $HAVE_MSVC_INVALID_PARAMETER_HANDLER = 1; then
14      REPLACE_DUP=1
15    fi
16  ])
17  dnl Replace dup() for supporting the gnulib-defined fchdir() function,
18  dnl to keep fchdir's bookkeeping up-to-date.
19  m4_ifdef([gl_FUNC_FCHDIR], [
20    gl_TEST_FCHDIR
21    if test $HAVE_FCHDIR = 0; then
22      REPLACE_DUP=1
23    fi
24  ])
25  AC_CACHE_CHECK([whether dup works], [gl_cv_func_dup_works],
26    [AC_RUN_IFELSE(
27      [AC_LANG_PROGRAM([[#include <unistd.h>
28                         #include <fcntl.h>
29                         #include <errno.h>
30                       ]GL_MDA_DEFINES],
31         [[/* On OS/2 kLIBC, dup does not work on a directory fd.  */
32           int fd = open (".", O_RDONLY);
33           return fd < 0 ? 1 : dup (fd) < 0 ? 2 : 0;
34         ]])
35      ],
36      [gl_cv_func_dup_works=yes],
37      [gl_cv_func_dup_works=no],
38      [case "$host_os" in
39                 # Guess no on native Windows.
40         mingw*) gl_cv_func_dup_works="guessing no" ;;
41         *)      gl_cv_func_dup_works="guessing yes" ;;
42       esac
43      ])
44    ])
45  case "$gl_cv_func_dup_works" in
46    *yes) ;;
47    *)
48      REPLACE_DUP=1
49      ;;
50  esac
51])
52
53# Prerequisites of lib/dup.c.
54AC_DEFUN([gl_PREREQ_DUP], [:])
55